Belgian rainfall radar detector at Jabbeke between Ostend and Bruges displayed a pattern of anomalous "rainfall" images around midnight on New Year's Eve.

Analysis has shown that these false images were generated by the radar detecting masses of birds that took off into the air when disturbed by fireworks being set off to celebrate the New Year.

http://tinyurl.com/lv8xsj9

Top image (1) (animation) shows a sudden mass of "rainfall" generated by birds in flight immediately after midnight, dying down within half an hour.

Still images show:
(2) the situation at 23.50 on New Year's Eve;
(3) and (4) the situation at 00.05 on New Year's Day, showing how the most intense "bird rainfall" is concentrated around two nature reserves where large numbers of water birds are present;
(5) a conventional rainfall radar picture with the anomalous bird images filtered out.

Colin Youngs
Brussels